Life Sciences Commons^™

Forest Floor And Mineral Soil Respiration Rates In A Northern Minnesota Red Pine Chronosequence, Matthew Powers, Randall K Kolka, John Bradford, Brian Palik, Martin F. Jurgensen

Michigan Tech Publications

We measured total soil CO₂ efflux (R_S) and efflux from the forest floor layers (R_FF) in red pine (Pinus resinosa Ait.) stands of different ages to examine relationships between stand age and belowground C cycling. Soil temperature and R_S were often lower in a 31-year-old stand (Y31) than in 9-year-old (Y9), 61-year-old (Y61), or 123-year-old (Y123) stands. This pattern was most apparent during warm summer months, but there were no consistent differences in R_FF among different-aged stands. R_FF represented an average of 4–13% of total soil respiration, and forest floor removal increased …

Quantitative Trait Locus Mapping Of Populus Bark Features And Stem Diameter, Roba Bdeir, Wellington Muchero, Yordan Yordanov, Gerald Tuskan, Victor B. Busov, Oliver Gailing

Michigan Tech Publications

Background

Bark plays important roles in photosynthate transport and storage, along with physical and chemical protection. Bark texture varies extensively among species, from smooth to fissured to deeply furrowed, but its genetic control is unknown. This study sought to determine the main genomic regions associated with natural variation in bark features and stem diameter. Quantitative trait loci (QTL) were mapped using an interspecific pseudo-backcross pedigree (Populus trichocarpa x P. deltoides and P. deltoides) for bark texture, bark thickness and diameter collected across three years, two sites and three biological replicates per site.

Results

QTL specific to bark texture …

Styrene-Assisted Maleic Anhydride Grafted Poly(Lactic Acid) As An Effective Compatibilizer For Wood Flour/Poly(Lactic Acid) Bio-Composites, Jun Du, Youyong Wang, Xinfeng Xie, Min Xu, Yongming Song

Michigan Tech Publications

This study aimed to evaluate the effect of styrene-assisted maleic anhydride-grafted poly(lactic acid) (PLA-g-St/MAH) on the interfacial properties of wood flour/poly(lactic acid) (PLA) bio-composites. PLA-g-St/MAH was synthesized by free-radical melt grafting using styrene as a comonomer and dicumyl peroxide as an initiator. The structure of PLA-g-St/MAH was characterized by Fourier transform infrared spectroscopy. Wood flour/PLA composites were prepared by compression molding using PLA-g-St/MAH as a compatibilizer. The effects of PLA-g-St/MAH on the rheological and mechanical properties, as well as on the fractured surface morphology of the composites were investigated. Results indicated that storage modulus, complex viscosity, equilibrium torque, and shear …

In-Class Cycling To Augment College Student Academic Performance And Reduce Physical Inactivity: Results From An Rct, Lanae Joubert, Matthew A. Kilgas, Alexandrea Riley, Yuba Gautam, Lars Donath, Scott Drum

Michigan Tech Publications

Most college students sit 14 hours per week on average, excluding sedentary study time. Researchers observing workplace and elementary school settings with active workstations to combat sedentary behavior have shown enhanced cognition without distraction. Until now, incorporating active workstations in college classroom settings remained relatively unexplored. This study’s purpose was to assess academic performance using in-class stationary cycle desks during a semester-long lecture course. Twenty-one college students (19–24 years) enrolled in a lecture course volunteered and were split into traditional sit (SIT) and stationary cycle (CYC) groups randomly, matched on a calculated factor equal to a physical activity (PA) score …

Spatially Varying Density Dependence Drives A Shifting Mosaic Of Survival In A Recovering Apex Predator (Canis Lupus), Shawn O'Neil, Joseph K. Bump, Dean E. Beyer

Michigan Tech Publications

Understanding landscape patterns in mortality risk is crucial for promoting recovery of threatened and endangered species. Humans affect mortality risk in large carnivores such as wolves (Canis lupus), but spatiotemporally varying density dependence can significantly influence the landscape of survival. This potentially occurs when density varies spatially and risk is unevenly distributed. We quantified spatiotemporal sources of variation in survival rates of gray wolves (C. lupus) during a 21-year period of population recovery in the Upper Peninsula of Michigan, USA. We focused on mapping risk across time using Cox Proportional Hazards (CPH) models with time-dependent covariates, thus exploring a shifting …

Comparison Of Thaumarchaeotal Populations From Four Deep Sea Basins., Stephen Techtmann, Nagissa Mahmoudi, Kendall T Whitt, Maria Fernanda Campa, Julian L Fortney, Dominique C Joyner, Terry C Hazen

Michigan Tech Publications

The nitrogen cycle in the marine environment is strongly affected by ammonia-oxidizing Thaumarchaeota. In some marine settings, Thaumarchaeotes can comprise a large percentage of the prokaryotic population. To better understand the biogeographic patterns of Thaumarchaeotes, we sought to investigate differences in their abundance and phylogenetic diversity between geographically distinct basins. Samples were collected from four marine basins (The Caspian Sea, the Great Australian Bight, and the Central and Eastern Mediterranean). The concentration of bacterial and archaeal 16S rRNA genes and archaeal amoA genes were assessed using qPCR. Minimum entropy decomposition was used to elucidate the fine-scale diversity of Thaumarchaeotes. We …

Carbon And Nitrogen Accumulation And Decomposition From Coarse Woody Debris In A Naturally Regenerated Korean Red Pine (Pinus Densiflora S. Et Z.) Forest, Nam Jin Noh, Tae Kyung Yoon, Rae-Hyun Kim, Nicholas Bolton, Choonsig Kim, Yowhan Son

Michigan Tech Publications

The contribution of coarse woody debris (CWD) to forest carbon (C) and nitrogen (N) dynamics is poorly quantified. This study quantified total C and N content in CWD and estimated the decomposition rates of CWD at different decay stages in a 70-year-old naturally regenerated Korean red pine forest (Pinus densiflora S. et Z.). The N concentration in CWD varied among species and decay classes (from 0.15% to 0.82%), and exhibited a decreasing pattern in C:N ratios with increasing decay class. Total CWD amounts of 4.84 Mg C ha⁻¹, dominated by pine logs (45.4%) and decay class III (40.0%), …

Risc-Interacting Clearing 3’- 5’ Exoribonucleases (Rices) Degrade Uridylated Cleavage Fragments To Maintain Functional Risc In Arabidopsis Thaliana, Zhonghui Zhang, Fuqu Hu, Min Woo Sung, Chang Shu, Claudia Castillo-González, Hisashi Koiwa, Guiliang Tang, Martin Dickman, Pingwei Li, Xiuren Zhang

Michigan Tech Publications

RNA-induced silencing complex (RISC) is composed of miRNAs and AGO proteins. AGOs use miRNAs as guides to slice target mRNAs to produce truncated 5’ and 3’ RNA fragments. The 5’ cleaved RNA fragments are marked with uridylation for degradation. Here, we identified novel cofactors of Arabidopsis AGOs, named RICE1 and RICE2. RICE proteins specifically degraded single-strand (ss) RNAs in vitro; but neither miRNAs nor miRNA*s in vivo. RICE1 exhibited a DnaQ-like exonuclease fold and formed a homohexamer with the active sites located at the interfaces between RICE1 subunits. Notably, ectopic expression of catalytically-inactive RICE1 not only significantly reduced miRNA levels; …

Selecting Habitat To What Purpose? The Advantage Of Exploring The Habitat-Fitness Relationship, Alessia Uboni, Douglas W. Smith, Daniel R. Stahler, John A. Vucetich

Michigan Tech Publications

Measures of reproductive success have been recognized in many fields as essential tools to assess the status of populations, species, and communities. However, difficulties in gathering data on reproductive success often prevent researchers from taking advantage of the information offered by those measures. For example, most of habitat selection studies do not include reproductive success in their analysis even though doing so would highly improve our understanding of the habitat selection process. In our study, we aimed to assess to what extent habitat selection choices made by adult individuals are directed to increase their annual reproductive success. We tested this …

Proteomic Profiling Of Vetiver Grass (Chrysopogon Zizanioides) Under 2,4,6-Trinitrotoluene (Tnt) Stress, Padmini Das, Dibyendu Sarkar, Rupali Datta

Michigan Tech Publications

Vetiver grass is an ideal plant for 2,4,6-trinitrotoluene (TNT) phytoremediation, due to its ability to tolerate and metabolize TNT as previously reported. The current study is the first attempt to investigate the changes in the proteomic profile of a plant under TNT stress. Vetiver plants were grown in nutrient media with varying concentrations of TNT (0, 25, 50, and 100 mg L−1) for 10 days. Although the plants appeared healthy, significant biomass reductions (p = 0.0008) were observed in treated plants. Total proteins in the root decreased significantly (p = 0.0003). Proteomic analysis of root proteins revealed the downregulation of …

The Relationship Of High-Intensity Cross-Training With Arterial Stiffness, Jamie F. Burr, Jenny L. Beck, John J. Durocher

Michigan Tech Publications

Background

Central arterial stiffness is a cardiovascular risk factor that can be readily affected through engagement in physical exercise training, with resistance and aerobic exercise having disparate affects. Despite the growing popularity of high-intensity cross-training (HICT), little is currently known about the effects of this mixed modality exercise stimulus on arterial stiffness. Therefore, the purpose of this study was to characterize the arterial stiffness of habitual HICT participants vs. aerobically active and sedentary controls using a cross-sectional design.

Methods

A total of 30 participants were recruited: 10 middle-aged long-term participants of HICT (CrossFit) and 20 age, sex, and height matched …

The Database Of The Predicts (Projecting Responses Of Ecological Diversity In Changing Terrestrial Systems) Project, Lawrence N. Hudson, Tim Newbold, Sara Contu, Samantha L.L. Hill, Igor Lysenko, Adriana De Palma, David J. Flaspohler, Et. Al.

Michigan Tech Publications

The PREDICTS project—Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)—has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in …

Applying Theory Of Constraints To Timber Harvesting: A Case Study From The Northeast Usa, Matthew Kelly, René H. Germain

Michigan Tech Publications

Logging firms are a critical link in wood supply chains, connecting forest landowners with markets for wood products. Improving operational planning can benefit individual logging firms as well as the larger wood supply chain in which they operate. Applying concepts from Theory of Constraints (TOC) to timber harvesting may help achieve greater predictability and efficiency when planning harvest operations. However, examples that demonstrate how TOC can improve logging operations are lacking. This study focuses on the analysis of production and activity data collected during the harvest of a temperate mixed hardwood forest in the Northeast United States using a chainsaw-forwarder …